In short, if you are intentionally guest blogging for the sole purpose of that post having a dofollow link to your site - Google would prefer that you nofollow the link. If you do not, you leave yourself open to a possible manual penalty.

That is the short of it. You can argue otherwise but if Google sees a guest blog post with a dofollow link and that person at Google feels the guest blog post is only done with the intent of a link, then they may serve your site a penalty. Or they may not - it depends on who is reviewing it.

That being said, Google is not to blame. While guest blogging and writing is and can be a great way to get exposure for your name and your company name, it has gotten to the point of being heavily abused.

A Cre8asite Forum thread has one SEO claiming that one site wanted to charge him £3,100 ($4,620 US dollars) for a guest blog post! Another site he contacted wanted £450 ($670 US dollars) for a guest post.

The number of email requests I get each day from people to pay me to post guest blog posts here is huge and the number keeps rising.

Truth is, guest blogging and writing although started for a good purpose, has been abused like many other real marketing tactics. Now, Google does have to take a closer look and also take action when they believe the intent is to manipulate their search results.